Development of a digital micro-manufacturing process for high frequencyultrasound transducers

Conventional methods for fabricating ultrasound imaging transducersespecially for high frequency (>20 MHz) range are expensive, time consumingand limited to relatively simple geometries. In this paper, the development ofan additive digital micro-manufacturing method for piezomaterials and compositesbased on digital micromirror devices (DMD) to be used in HF ultrasoundtransducers is presented. Photocured piezoelectric materials with micro-scalefeatures were fabricated. Different piezoelectric characteristics of thematerials have been tested and compared with the bulk case. The Density of thefabricated samples was increased by applying hot uniaxial press and adding PZTcomposite sol-gel to the photocure solution. The dielectric constant(η_r) and the tangent loss (tgθ) of the samples at 1 KHzwere found to be around 610 and 0.025, respectively. The measured piezoelectricconstant (d₃₃) of the fabricated samples was around 156×10^-12 C/N, and the sound velocity about 1850 m/s. The polarization(P_r) and the coercive field (E_c) were 18 μC/cm and 80kV/cm, respectively.